300-420 Question 257
Single answerA network engineer is tasked with designing a network solution to manage traffic flows on a branch office router. The goal is to ensure that excess traffic beyond the committed rate is dropped while maintaining a hard limit on bandwidth usage. Which QoS mechanism should the engineer use to meet this requirement?
- A
Traffic shaping
- B
Policing
- C
Weighted Fair Queuing (WFQ)
- D
Class-Based Weighted Fair Queuing (CBWFQ)
Show answer and explanation
Correct answer: B
Explanation
Policing is the correct QoS mechanism in this scenario because it strictly enforces the committed rate by dropping traffic that exceeds the configured limit. Unlike traffic shaping, policing does not buffer excess traffic, making it the best choice for scenarios where a hard limit on bandwidth is required.
- A. Incorrect.
Traffic shaping buffers excess traffic and sends it at a later time, which smooths the traffic rate but does not strictly enforce a hard bandwidth limit by dropping packets. This does not meet the requirement.
- B. Correct.
Policing enforces a hard bandwidth limit by dropping excess traffic beyond the committed rate. This matches the requirement of the scenario.
- C. Incorrect.
Weighted Fair Queuing (WFQ) is a queuing mechanism that prioritizes traffic flows but does not enforce bandwidth limits or drop packets based on rate, making it unsuitable for this scenario.
- D. Incorrect.
Class-Based Weighted Fair Queuing (CBWFQ) extends WFQ with class-based prioritization but does not enforce a hard bandwidth limit or drop excess traffic. This option does not meet the requirement.